Inorg. Chem. 1987,26, 3533-3538 the electrical charge of the redox-active metal ions. In particular, it has been shown that its effective value varies with the nature of the metal and with its stereochemical arrangement. Moreover, the bulk value of the dielectric constant of the medium is absolutely not appropriate to describe the shielding effect exerted by the solvational molecules. In particular, in strongly saline solutions, the ions of the so-called “inert electrolyte” may substantially modify the solvation state of the dimetallic system and seriously affect its redox behavior. The only parameter of Coulomb’s law whose role seems to be accounted for, in a quantitative sense, is the distance between metal centers. Due to the stretched arrangement of the joining chain, its value can be calculated on the basis of molecular models. Acknowledgment. Financial support by the Italian Ministry of Public Education (MPI 40%) is gratefully acknowledged. Registry No. 1, 295-37-4; 2, 110078-38-1; 2a, 110078-39-2; 3, 110078-40-5; 3a, 110078-41-6; 4, 110078-42-7; 4a, 110078-43-8; 4b, 110078-48-3; 5, 110078-44-9; 5a, 110078-45-0; 6, 110078-46-1; 6a,
3533
110078-47-2; 7,104395-69-9; [C~2(2)](Cl04)4,110095-31-3; [ C ~ 2 ( 2 ) ] ~ + , 110095-60-8; [Cu2(2)I6’, 110095-50-6; [C~2(3)](ClO4)4,110095-33-5; [C~2(3)]”, 110095-61-9; [C~2(3)]~’, 110095-51-7; [C~2(4)](ClO4)4, 110095-35-7; [C~2(4)]’+,110095-62-0; [C~2(4)]~’,110095-52-8; [ C U ~ (5)](ClO4)4, 110095-37-9; [ C ~ 2 ( 5 ) ] ” , 110095-63-1; [Cu2(5)I6+, 110095-53-9; [C~2(6)](ClO4)4,110095-39-1; [C~2(6)]”, 110095-64-2; [Cu2(6)I6+, 110095-54-0; [Ni2(2)](C104)4, 110095-41-5; [Ni2(2)Is+, 110095-65-3; [Ni2(2)I6+, 110095-55-1; [Ni2(3)](C104)4,110095-43-7; [Ni2(3)l5+, 110095-66-4; [Ni2(3)I6+, 110095-56-2; [Ni2(4)](CIO4),, 110095-45-9; [Ni2(4)I5’, 110095-67-5; [Ni2(4)I6+,110095-57-3; [Ni2(5)](C104)4, 110095-47-1; [Ni2(5)I5+, 110095-68-6; [Ni2(5)I6+, 110095-58-4; [Ni2(6)](C104)4, 110095-49-3; [Ni2(6)lS’, 110095-69-7; [Ni2(6)I6’, 110095-59-5; T s O C H 2 C H 2 0 T s , 6315-52-2; TsOCH2CH2CH20Ts, 5469-66-9; TsCI, 98-59-9; BrCH2-m-C6H4CH2Br,626- 15-3; BrCH2-p-C6H4-CH2Br,623-24-5; COC1(CH2)2COCI, 543-20-4. Supplementary Material Available: A table containing melting points and analytical data (C, H, N ) of the bis(macrocyc1es) 2-4 and of their protected precursors (1 page). Ordering information is given on any masthead page.
Contribution from the School of Science, Griffith University, Brisbane, Australia 41 11, Department of Physical and Inorganic Chemistry, University of Western Australia, Perth, Australia 6009, and Department of Chemistry, University of Auckland, Auckland, New Zealand
Lewis-Base Adducts of Group 11 Metal(1) Compounds. 32. Steric Effects in the 2:l Adducts of (2-Methylpheny1)diphenylphosphine with Copper(I) Halides Graham A. Bowmaker,la Lutz M. Enge1hardt,lb Peter C. Healy,*lCJohn D. Kildea,lb Rocco I. Papasergio,lb and Allan H. Whitelb Received April I, 1987 Solid-state 31P N M R spectra, far-infrared spectra, and single-crystal X-ray structure determinations have been recorded for (2-methylpheny1)diphenylphosphine(PPh2-o-tol) and its mononuclear 2: 1 adducts with copper(1) halides, (PPh2-o-tol)2CuX. The solid state ,IP N M R spectrum of the ligand shows a single sharp resonance at -18 ppm with respect to 85% H3P04. The spectra of the 2:l adducts show two sets of overlapping asymmetric quartets for the chloride and bromide and a single broad quartet for the iodide, indicating the presence of at least two crystallographically distinct ligands in the first two compounds and one in the third. Average chemical shift values (ppm) are as follows: C1, -1 1; Br, -11; I, -15. The asymmetry in the line spacing for each quartet is consistent with a trigonal coordination geometry around the copper atom. Far-infrared spectra of each of the metal complexes in the range 50-400 cm-’ show strong bands that are assigned to terminal metal-halogen stretching vibrations: Cu-Cl, 290 cm-I; Cu-Br, 220 cm-I; Cu-I, 200 cm-’. The parent ligand crystallizes in the monoclinic space group P2,/c with a = 10.713 (5) A,b = 8.726 (5) A,c = 16.573 (6) A,fi = 90.77 (3)O, and 2 = 4. All three copper structures crystallize in the monoclinic space group C2/c. The CI and Br structures are isomorphous with one complete molecule of (PPh2-o-tol)2CuX comprising the asymmetric unit. For X = CI, a = 22.413 (15) A,b = 16.034 (4) A, c = 19.092 (2) A,@ = 107.04 (4)O, and 2 = 8; for X = Br, a = 22.348 (7) A, b = 16.033 (8) A,c = 19.526 (5) A, fi = 108.73 (2)O, and 2 = 8. However, for X = I, a = 18.665 (5) A,b = 10.006 (2) A, c = 19.764 (5) A,fi = 115.29 (2)O, and Z = 4, with the two ligands related by symmetry and the Cu-I bond sited on the 2-fold rotation axis. For X = CI, Cu-P, Cu-P, Cu-X, and P-Cu-P = 2.241 (2) A,2.257 (2) A, 2.205 (2) A, and 126.96 (7)O respectively; for X = Br, the values are 2.240 (2) A,2.255 (2) A, 2.336 (1) A,and 127.89 (7)O, respectively; and for X = I, Cu-P, Cu-I, and P C u - P = 2.255 (1) A,2.507 (1) A,and 126.36 (7)O, respectively. Both Cu-P and Cu-X distances are similar to the corresponding values for (PPh3)2CuXcompounds. However, as a consequence of changes in steric profile, the conformational structure of each ligand about the Cu-P bonds with respect to Cu-X is significantly different.
Introduction Reaction of copper(1) halides, CuX, with tertiary organophosphine bases, PR3, gives a wide range of products of variable stoichiometry and molecular structure. Most structural studies have been reported for compounds of 1:l stoichiometry, [PR3CuX],, and here the stellaquadrangulaZor “cubane” structure is most common, crystallographic data being reported for a wide range of bases with differing steric and electronic characteristics including PEt3 with X = Cl,3 Br,3 and I;4 PMePhz with X = I;5 PPh3 with X = C1,6 Br,7 and I,8 and P(t-Bu), with X = Br? For (1) (a) University of Auckland. (b) University of Western Australia. (c) Griffith University. (2) Noren, B.;Oskarsson, A. Acta Chem. Scand. Ser., A 1985, A39, 701. (3) Churchill, M.R.; DeBoer, B. G.; Mendak, S. J. Inorg. Chem. 1975,14, 2041. (4) Churchill, M. R.; Kalra, K. L. Inorg. Chem. 1974, 13, 1899. (5) Churchill, M.R.; Rotella, F. J. Inorg. Chem. 1977, 16, 3267.
0020-1669/87/1326-3533$01.50/0
PPh3 and X = Br and I, a change of solvent results in the crystallization of the alternative “step” tetramer.1° For the ligands, P ( ~ h x (chx ) ~ = cyclohexyl) with X = C1 and P(mes)3 (mes = mesityl) with X = Br, dimeric [PR3CuXI2l1and monomeric [PR3CuX]l 2 structures, respectively, are obtained. By contrast, (6) Clayton, W. R;Shore, S. G. Cryst. Struct. Commun. 1973, 2, 605; Churchill, M.R.; Kalra, K. L. Inorg. Chem. 1974, 13, 1065. (7) Barron, P. F.; Dyason, J. C.; Engelhardt, L. M.; Healy, P. C.; White, A. H. Inorg. Chem. 1984, 23, 3766. (8) Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.; Pakawatchai, C.; Patrick, V. A.; Raston, C. L.; White, A. H. J . Chem. SOC.,Dalton Trans. 1985, 831. (9) Goel, R. G.;Beauchamp, A. L. Inorg. Chem. 1983, 22, 395. (10) Dyason, J. C.;Engelhardt, L. M.; Pakawatchai, C.; Healy, P. C.; White, A. H. Aust. J . Chem. 1985, 38, 1243 and references therein. (11) Churchill, M. R.; Rotella, F. J. Inorg. Chem. 1979, 18, 166. (12) Alyea, E. C.;Ferguson, G.;Malito, J.; Ruhl, B. L. Inorg. Chem. 1985, 24, 3720.
0 1987 American Chemical Society
3534 Inorganic Chemistry, Vol. 26, No. 21, 1987 structural data for compounds with ligand to CuX stoichiometric ratios greater than one are scarce. PPhH213and PMePh2I4with X = I have been shown to crystallize as 2:l dimers, (PR3)2CuX2Cu(PR,)2and 3:l monomers have been reported for PMePhz with X = CII4 and for PPh, with X = Cl,'49'5 Br,15,and I.15 PPh, yields, under special conditions, a 2:l monomer, L2CuX, with X = C1,16 Br," and 1,16 the more common product from solutions of this stoichiometry being the structurally unique 1.5:l dimer, ( P R 3 ) 2 C ~ X 2 C ~ ( P R 3 ) . 1 0 The generalization has often been made that the molecular structure for a given complex within this series is controlled primarily by the size of the ligand, which is usually defined in terms of the Tolman cone angle.l8 While this is undoubtedly a good first approximation, inconsistencies in the structural results exist. For example, despite its larger cone angle, P ( t - B ~ ) ~ c u B r is tetrameric while P(chx),CuCl is dimeric; i.e. the ligand proas well must be taken into account in predicting structural properties. The structural chemistry of [ (PP~,)CUX],,~-* [(PPh3)3(CuX)2],10and [(PPh3),CuX] l5 has indicated that solvent interactions may also be important in stabilizing different molecular geometries in this system, and our recent work on the structural chemistry of the monomeric (PPh3)2CuXsystem16has shown as well that halide-phenyl c-hydrogen interactions also may play a role. Given this array of results, it seemed likely that quite small ortho modifications on the ligand could substantially affect the structure and chemical reactivity of the compounds obtained and to test this we prepared the ligand (2-methylphenyl)diphenylphosphine, PPh,-c-tol, and reacted it with CuCI, CuBr, and CUIin a 2:l molar ratio in acetonitrile solution to give white crystalline precipitates. Chemical analyses on the compounds obtained showed that the sole products had the stoichiometric formula (PPh,-o-tol),CuX and both solid-state ,*PN M R and far-infrared spectroscopic data strongly supported the molecular structure of each as monomeric rather than dimeric. This was subsequently confirmed by single-crystal X-ray structure determinations, and the results of this work are presented here, together with an analysis of the effects of the steric profile of the ligand and X-H interactions on the molecular structure. Experimental Section Preparation of PPh2-o-tol. A solution of 60 mL of chlorodiphenylphosphine in 60 mL of tetrahydrofuran was added to 150 mL of a 2.03 M solution of CH3C6H4MgC1in tetrahydrofuran at -78 OC. The mixture was warmed to room temperature and left to srand for 2 h; the solvent was removed in vacuo and the residue extracted with dichloromethane and then concentrated to a pale brown oil. A 200-mL aliquot of ethanol was added and the solution cooled to -30 OC to yield white crystals, mp 69-71 OC (lit.*" 66-67 "C). Anal. Calcd for CI9H17P:C, 82.6; H, 6.2. Found: C, 82.1; H, 6.3. Preparation of (PPh2-o-tol)2CuX.All three complexes were prepared similarly. A 0.001-mol sample of the copper halide was dissolved in degassed acetonitrile, and slightly more than 0.002 mol of the ligand was added. White crystalline precipitates formed immediately. Dissolution by heating followed by slow cooling gave clear colorless crystals of the compounds. Mp: X = C1, 209-215 O C ; X = Br, 224-228 OC;X = I, 218-222 OC. Anal. Calcd for C38H34CuClP2:C, 70.0; H , 5.3. Found: C, 70.4; H , 5.4. Calcd for C38H34C~BrP2: C, 65.6; H, 4.9. Found: C, 65.2; H, 5.0. Calcd for C38H34C~IP2: C, 61.4; H, 4.6. Found: C, 61.6; H, 4.7. Spectroscopy. Solid-state IIP spectra of the compounds were obtained at room temperature on a Bruker CXP-300 spectrometer at 121.47 MHz (13) Batchelor, R.J.; Birchall, T.; Faggiani, R. Can. J . Chem. 1985,63, 928. Gill, J. T.; Mayerle, J. J.; Welcher, P. S.; Lewis, D. F.; Ucko, D. A. Barton, D. J.; Stowens, D.; Lippard, S . J. Inorg. Chem. 1976, IS, 1155. Barron, P. F.; Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.: Pakawatchai, C.: Patrick, V. A,; White, A. H. J. Chem. Soc., Dalton Trans. 1987, 1099. Bowmaker, G . A,; Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.; Pakawatchai, C.; White, A. H. J . Chem. SOC.,Dalton Trans. 1987, 1089.
Davis, P. H.; Belford, R. L.; Paul, I. C. Inorg. Chem. 1973, 12, 213. Tolman, C. A. Chem. Rev. 1977, 77, 313. Ferguson, G.:Roberts, P. J.; Alyea, E. C.: Khan, M. Inorg. Chem. 1978, 17, 2965. Grim, S. 0.; Yankowsky, A. W. Phosphorus Sulfur 1977, 3, 191.
Bowmaker et al.
20
0
-20
ppm
Figure 1. 31P solid-state N M R spectra: (a) (PPh2-o-tol)2CuC1; (b) (PPh2-o-tol)2CuBr; (c) (PPh,-~-tol)~CuI. Table I. Solid-state N M R Data for (PPh2-o-tol),CuX Compounds" chem shifts line spacing/ 1O3 Hz X 61 6 2 63 64 (6) A u ~ A U ~ Pug A~jj C1 6 -2 -12 -24 -8 0.90 1.25 1.40 0.50 1 -7 -18 -32 -14 0.95 1.30 1.60 0.65
Br
7 1
-2 -8
-11 -18
-23 -31
-7 -14
1.00 1.05
1.15 1.30
1.40 1.55
0.40 0.50
I
1
-8
-20
-31
-15
1.10
1.40
1.40
0.30
" b j are chemical shift values with respect to 85% H 3 P 0 4 via PPh3 (-9.9 ppm). Where peaks overlap, the 6 value quoted is an estimate only. ( 6 ) is the average chemical shift for each quartet. Auj is the line spacing between each of the four peaks of each quartet. Auij = Aut(max) - Auj(min) is defined here as an estimate of the asymmetry parameter of the quartet. using IH-)'P cross-polarization with radiofrequency fields of 8 and 20 G , respectively, as described previously.' Chemical shift data were referenced to 85% H3P04 via solid triphenylphosphine (6(PPh3)= -9.9 ppm) (Figure 1, Table I). Far-infrared spectra were recorded at ca. 298 and 125 K as petroleum jelly mulls between polyethylene plates on a Grubb-Parsons Mk I1 cube interferometer interfaced to an IBM P C microcomputer and were calibrated against the spectrum of water vapor (Figure 2). Structure Determinations. A summary of crystal data is presented in Table 11. Unique data sets were measured to the specified ,,28, limits on specimens mounted in capillaries by using Syntex Pi and ENRAF Nonius CAD-4 four-circle diffractometers (monochromatic Mo K a radiation sources, X = 0.71069 A) in conventional 28/9 scan mode, at 295 K. N independent reflections were measured, No with I > 2,3a(I) being considered "observed" and used in the full-matrix least-squares refinement with statistical weights after solution of the structures by the heavy atom method. ( x , y , z, were included at idealized values for the ligand, chloride, and bromide complexes. (x, y , z ) were ~ refined for the iodide complex. Residuals on 1 4at convergence were conventional R and R'. Each structure refined smoothly in the chosen space group with no
Inorganic Chemistry, Vol. 26, No. 21, 1987 3535
Lewis-Base Adducts of Group 11 Metals Table 11. Summary of Crystal Data for PPh2-o-to1and (PPh2-o-tol)2CuX
PPh2-O-to1
(PP~~-o-~oI)~CUCI (PPh,-~-tol)~CuBr C ~ ~ H ~ ~ C U C I P ~ C38H34C~BrP2
C38H34Cu1P2
651.7
696.1
743.1
monoclinic
monoclinic
monoclinic
monoclinic
P2,lC 10.713 (5) 8.726 (5) 16.573 (6) 90.77 (3) 1549 (1) 4 1.17 (2) 1.18 584 1.74 0.25 X 0.25 X 0.25
c2/c 22.413 (15) 16.034 (4) 19.092 (2) 107.04 (4) 6560 (2) 8 1.30 (2) 1.32 2704 9.0 0.25 X 0.25 X 0.25
c2/c 22.348 (7) 16.033 (8) 19.526 (5) 108.73 (2) 6626 (2) 8 1.41 (2) 1.40 2848 20.9 0.24 X 0.16 X 0.16
no
no
analytical
C2lC 18.665 (5) 10.006 (2) 19.764 (5) 115.29 (2) 3337 (2) 4 1.50 (2) 1.48 1496 17.5 0.30 X 0.20 X 0.10 no
45 2036 1066 I > 34I) 181 0.061 0.082
45 2904 2285 I>2 4 0 380 0.044 0.040
1.32; 1.39 45 4234 2895 I > 24I) 380 0.059 0.034
50 2957 2002 I > 34I) 243 0.033 0.034
formula
C19H17P
fw
276.3
cryst syst space group
Pldeg
vl~3
2
D,lg D,lg F(000)
CIMo/cm-’ cryst size/mm abs cor A*min; A*mx
2emaxldeg
N No
condition ind var
R R‘
(PPh2-0-t01)2CuI
Table 111. Non-Hydrogen Atom Coordinates for PPh2-o-tol
atom
~
50
~
100
~
150
200
250
300
350
400
Wavenumber (cm-1)
Figure 2. Far-infrared spectra: (a) (PPh2-o-tol)2CuC1;(b) (PPh2-otol)*CuBr;(c) (PPh2-o-tol)2CuI.
anomalies with respect to features such as thermal envelopes or disorder. Neutral-atom complex scattering factors were used.21 No significant extinction effects were observed. Computation used the XTAL83 program system22implemented by S.R. Hall on a Perkin-Elmer 3240 computer, and the APPLECRYST program package, written by C. H. L. Kennard for an Apple IIe microcomputer. Non-hydrogen atom coordinates are given in Tables 111-VI; the atom-labeling scheme adopted for the PPh,-o-tol ligands is as described in ref 15. The ortho carbon atoms, C(lm2) ( m (21) Ibers, J. A,, Hamilton, W. C., Us.International Tables for X-ray Crystallography; Kynoch: Birmingham, England, 1974; Vol. IV. (22) Stewart, J. M., Hall, S. R., Eds. “The XTAL System of Crystallographic Programs: Users Manual”; Technical Report TR-901; Computer Science Center, University of Maryland: College Park, MD, 1983.
X
Y
Z
0.6654 (3) 0.805 (1) 0.819 (1) 0.734 (2) 0.916 (2) 1.009 (2) 0.994 (1) 0.890 (1) 0.721 (1) 0.626 (1) 0.665 (2) 0.789 (2) 0.873 (1) 0.841 (1) 0.666 (1) 0.624 (1) 0.614 (1) 0.644 (1) 0.685 (1) 0.697 (1)
0.2422 (4) 0.131 (2) -0.009 (2) -0.074 (2) -0.098 (2) -0.051 (2) 0.090 (2) 0.180 (1) 0.349 (1) 0.400 (1) 0.483 (2) 0.512 (2) 0.460 (2) 0.378 (2) 0.392 (2) 0.348 (1) 0.453 (2) 0.603 (1) 0.648 (1) 0.544 (2)
0.4167 (2) 0.3911 (7) 0.4282 (8) 0.4887 (8) 0.4101 (9) 0.3565 (10) 0.3192 (8) 0.3374 (8) 0.5063 (6) 0.5596 (8) 0.6286 (8) 0.6449 (8) 0.5931 (9) 0.5249 (8) 0.3390 (7) 0.2623 (8) 0.2011 (8) 0.2146 (8) 0.2901 (9) 0.3520 (7)
= ring number 1, 2, or 3) are outside the PC3pyramid. Pertinent geometric parameters are given in Tables VI1 and VIII. Results and Discussion Solid-state 31PNMR Spectra. The solid-state CPMAS 31P N M R spectrum of the ligand gives a single sharp line at -18 ppm with respect to 85% H3PO4which is ca. 5 ppm upfield from the reported solution value of -13 ppm, recorded in CH2C12solution.” The spectra of the complexes show broad signals of relatively low intensity. The chloride and bromide spectra can be resolved into two overlapping quartets whereas the iodide is better described as consisting of one broad quartet only (Figure 1 ) . These results are consistent with the crystallographic data. Although all three complexes crystallize in space group C2/c, the asymmetric units of the isomorphous chloride and bromide structures contain the entire molecule with each PPh2-o-to1 ligand adopting distinctly different conformational structures (Table VII), whereas for the iodide structure the two ligands are related by a 2-fold rotation symmetry operation, the rotation axis lying along the Cu-I vector. The average chemical shift values for each compound of C1 = -1 1, Br = -1 1, and I = -15 ppm represent a 3-7 ppm downfield shift from that of the parent ligand, a similar downfield shift also being found for (PPh3)2C~X.’6More compelling evidence of the structural similarities between the two series of compounds is, however, the magnitude and asymmetry of the line spacing with the magnitude varying from a value of 0.9 X lo3 Hz for the
3536 Inorganic Chemistry, Vol. 26, No. 21, 1987
Bowmaker et al.
Table IV. Non-Hydrogen Atom Coordinates for (PPh2-o-tol)2CuC1 atom X V Z 0.43254 (5) 0.10348 (4) cu 0.26108 (3) 0.3245 (1) 0.1780 (1) Cl 0.28323 (8) 0.5152 (1) 0.09517 (8) 0.33933 (7) P(1) 0.05870 (8) 0.4583 (1) 0.15789 (7) P(2) 0.1106 (3) 0.4159 (2) 0.4680 (4) C(111) 0.1476 (3) 0.4285 (3) 0.3941 (4) C(112) 0.1615 (4) 0.4876 (3) 0.3582 (5) C(113) 0.1402 (4) 0.5333 (3) 0.3964 (5) C(114) 0.1025 (5) 0.5213 (3) 0.4686 (5) C(115) 0.0867 (4) 0.4626 (3) 0.5046 (4) C(116) 0.3508 (2) 0.5929 (3) C(121) 0.1676 (3) 0.6289 (4) 0.1802 (3) 0.3000 (3) C( 122) 0.3062 (3) 0.6866 (4) C(123) 0.2356 (4) 0.7071 (5) 0.2792 (4) 0.3619 (3) C(124) 0.6727 (6) 0.2672 (5) 0.4141 (3) C(125) 0.4086 (3) 0.6149 (5) C( 126) 0.2114 (4) 0.5755 (4) 0.0121 (3) 0.3298 (2) C(131) 0.3147 (2) 0.5350 (4) C( 132) -0.0554 (3) 0.3056 (3) 0.4419 (4) C(1321) -0.0632 (3) 0.5826 (5) -0.1191 (3) 0.3073 (3) C(133) 0.3138 (3) C( 134) -0.1 157 (4) 0.6670 (5) -0.0498 (4) 0.7075 (4) 0.3282 (3) C(135) 0.0132 (4) 0.3360 (3) C( 136) 0.6619 (4) 0.1044 (2) C(211) 0.0531 (3) 0.3711 (3) 0.1 124 (3) 0.0171 (3) 0.2978 (4) C(212) -0.0163 (4) 0.1654 (3) C(2121) 0.2870 (5) 0.0699 (3) C(213) 0.2341 (4) 0.0122 (4) 0.0394 (4) C(214) 0.2408 (4) 0.0200 (3) 0.3117 (4) 0.0756 (3) 0.0128 (3) C(215) 0.0822 (3) C(216) 0.3767 (4) 0.0541 (3) 0.1197 (3) C(221) OS321 (3) 0.1362 (2) 0.5251 (4) 0.1933 (3) 0.1642 (3) C(222) 0.2418 (4) C(223) 0.5804 (5) 0.1517 (3) 0.2164 (4) 0.6444 (5) 0.1107 (3) C(224) 0.6520 (4) 0.1433 (4) C(225) 0.0814 (3) 0.0942 (3) C(226) 0.5962 (4) 0.0937 (3) 0.5061 (4) 0.1296 (2) -0.0313 (3) C(231) 0.5714 (4) -0.0495 (3) C(232) 0.1628 (2) -0.1185 (3) C(233) 0.6083 (4) 0.1430 (3) -0.1686 (3) 0.5799 (5) 0.0898 (3) C(234) 0.5147 (5) -0.1523 (3) C(235) 0.0565 (3) 0.4791 (4) -0.0835 (3) C(236) 0.0760 (3)
Table V. Non-Hydrogen Atom Coordinates for (PPh,-o-tol),CuBr atom X Y Z cu 0.26251 (4) 0.10117 (4) 0.28728 (4) Br 0.31966 (6) 0.18186 (5) 0.34118 (8) 0.5150 (1) 0.09520 (9) P(1) 0.15765 (8) 0.05665 (9) 0.4557 (1) P(2) 0.4189 (3) 0.1 105 (3) 0.4706 (4) C(111) 0.4358 (3) 0.3990 (4) C(112) 0.1490 (3) 0.4962 (3) C(113) 0.1642 (4) 0.3653 (5) 0.5391 (3) 0.1416 (4) 0.4030 (5) C(114) OS237 (3) C(115) 0.1025 (4) 0.4730 (5) 0.4637 (3) 0.0863 (4) 0.5078 (5) C(116) 0.3534 (3) C(121) 0.1672 (3) 0.5907 (4) 0.3023 (3) 0.6235 (4) C( 122) 0.1810 (4) 0.3063 (3) C( 123) 0.6796 (5) 0.2358 (4) 0.3643 (3) 0.7034 (5) C( 124) 0.2772 (4) 0.4155 (3) 0.6733 (6) C(125) 0.2649 (5) 0.4098 (3) 0.6173 (5) C( 126) 0.2101 (4) 0.3294 (2) C(131) 0.5766 (4) 0.0131 (3) 0.3132 (3) 0.5366 (4) C( 132) -0.0539 (3) 0.3048 (3) 0.4451 (4) C(1321) -0.0632 (3) 0.3045 (3) C(133) 0.5856 (5) -0.1153 (3) 0.3107 (3) 0.6699 (5) C( 134) -0.1115 (4) 0.3245 (4) C(135) -0.0460 (4) 0.7089 (4) C(136) 0.3350 (3) 0.6627 (4) 0.0164 (4) 0.1049 (2) C(211) 0.3681 (4) 0.0508 (3) 0.1117 (3) C(212) 0.2955 (4) 0.0142 (3) 0.1623 (3) C(2121) 0.2856 (5) -0.0192 (4) 0.0685 (3) 0.2315 (4) 0.0088 (3) C(213) 0.0197 (3) C(214) 0.2376 (4) 0.0357 (4) 0.0133 (3) 0.3082 (4) 0.0725 (3) C(215) 0.0558 (3) 0.3727 (4) C(216) 0.0794 (3) 0.1369 (3) 0.5274 (4) 0.1171 (3) C(221) 0.1633 (3) 0.5156 (4) 0.1912 (3) C(222) C(223) 0.1501 (3) 0.5697 (5) 0.2390 (3) 0.1120 (3) 0.6376 (4) 0.2144 (4) C(224) 0.0851 (3) 0.6492 (4) 0.1424 (4) C(225) 0.5951 (4) 0.0929 (3) C(226) 0.0974 (3) C(231) 0.1266 (3) 0.5035 (4) -0.0322 (3) 0.1605 (3) 0.5687 (4) -0.0492 (3) C(232) 0.1392 (3) 0.6059 (4) -0.1 170 (3) C(233) C(234) 0.0850 (3) 0.5791 (5) -0.1672 (3) C(235) 0.0517 (3) 0.5153 (4) -0.1506 (3) 0.0713 (3) 0.4783 (4) -0.0837 (3) C(236)
spacing between the low-field lines to 1.6 X lo3H z between the high-field lines, which are, within experimental error, the same as corresponding values for (PPh3)2CuX. Infrared Spectra. The infrared spectra in the region 50-400 cm-' of each of the three metal complexes, recorded at ca. 125 K, are illustrated in Figure 2. The spectrum of the ligand shows weak bands at 210, 235,and 275 cm-' that are essentially unchanged on coordination with the metal. In the spectra of the three complexes, strong bands are observed at 290,220,and 200 cm-' for the C1, Br, and I compounds, respectively. For comparison, the spectra of monomeric (PPh3)2CuXcompounds show similar bands at 290,220,and 185 cm-', these being assigned to the terminal M-X stretching vibrations,16 and a parallel assignment in the present complexes seems reasonable. Crystal Structures. The parent ligand exists as discrete molecules with the o-methyl group on the same side of the ligand as the lone pair on the phosphorus atom (Fi ure 3). The P-C distances of 1.84 (l), 1.84(l), and 1.83 (1) (( 1.84 (1) A)) are very similar to those of the two "parent- ligands: for PPh3,231.822 (5), 1.831 (5), and 1.831 (5) A ((1.83 (1) A)); for P(~3-tOl)j,~~ 1.837 (2), 1.836 (2), 1.836 (2), 1.837 (2), 1.836 (2),and 1.830 (2)8, (( 1.83 (1) A)). The same is true for C-P-C angles 101.2 (6), 101.5 (5), and 101.8 (6)' ( ( 101.5 (2)')): for PPh,, 103.6 (2), 102.1 (2), and 103.3 (2)O ((103.0 (5)')); for P(o-tol)3 molecule 1, 101.9 (l), 103.1 (l), and 103.4 (1)'; for P(o-tol), molecule 2, 101.6 (l), 102.7 (l), and 102.9(1)' ((102.6(3)')). (Standard errors are calculated from the available range of dis-
Table VI. Non-Hydrogen Atom Coordinates for (PPh,-o-tol),CuI
i
~
~
~
~
atom
X
0 0 0.02162 (7) 0.0598 (3) 0.1322 (3) 0.1789 (3) 0.1608 (4) 0.120s (4) 0.0496 (4) 0.0186 (3) -0.0772 (3) -0.1390 (3) -0.2164 (3) -0.2328 (3) -0.1724 (3) -0.0940 (3) 0.0802 (3) 0.0947 (3) 0.1310 (3) 0.1561 (3) 0.1449 (3) 0.1072 (3)
Y 0.20764 (8) -0.04289 (5) 0.3093 (1) 0.2140 (5) 0.1458 (5) 0.1456 (7) 0.0777 (6) 0.0764 (7) 0.1415 (7) 0.2108 (5) 0.3647 (5) 0.2750 (6) 0.3136 (7) 0.4389 (7) 0.5286 (6) 0.4917 (5) 0.4625 (5) 0.5308 (5) 0.6545 (6) 0.7073 (6) 0.6386 ( 6 ) 0.5162 (5)
2
'/*
'14
0.35886 (6) 0.4465 (2) 0.4692 (3) 0.4231 (3) 0.5365 (3) 0.5808 (3) 0.5587 (3) 0.4910 (3) 0.3448 (2) 0.3104 (3) 0.2936 (4) 0.3100 (3) 0.3435 (3) 0.3611 (3) 0.3849 (2) 0.3312 (3) 0.3466 (3) 0.4175 (3) 0.4721 (3) 0.4563 (2)
tances and angles.) In these P(aryl), compounds, the angles of intersection between the normals to the planes of the phenyl rings approach 90° in order to minimize the packing energy in these structure^.^^ For example: PPh,, 84,77,and 78'; PPh2-o-tol,
~
(23) Daly, J. J. J . Chem. SOC.1964, 3799. (24) Cameron, T. S.;Dahlen, B. J . Chem. Soc., Perkin Trans. 2,1975, 1737.
(25) Piermarini, G. J.; Mighall, A. D.; Weir, C. E.; Block, S. Science (Washington, D.C.) 1969, 157, 1250.
Lewis-Base Adducts of Group 11 Metals
Inorganic Chemistry, Vol. 26, No. 21, I987 3531
Table VII. Conformational Angles (deg) for Mononuclear (PR3)2CuXCompounds X-Cu-P(1)-C( Im 1)
compd (PPh2-o-t01)2CuCI
I
1 2 (PPh2-o-tol),CuBr 1 2 ( P P ~ ~ - ~ - ~ O I ) ~ C U I1 (PPh3)2CuCla 1 2 (PPh3)2C~Br' 1 2 (PPh&$hI' 1
m = l -30 26 -32 28 -14
m=2 87 -92 84 -89
2
10 -1 13
5
Cu-P(1)-C(lm 1)-C(/m2)
m=3 -155
m = l 20 53 23 54
151
103
-158 153 -143
119 -1 16 117 -1 13 -118
-121 127 -124 130 124
-58
m=2 43 37 40 43 -43
m=3 55 43 56 42 -1 5
-53 -51 -53 -50 -37
-38 -63 -39 -63 -61
-37 -17 -39
-19 -35
Reference 16. Table VIII. Core Geometries for (PPh,-o-tol),CuX and (PPh?),CuX
P-M-P/ den
0
@c'
P-M-X J den
A
-
P
compd M-PIA M-XIA ( P P ~ ~ - ~ - ~ O I ) ~ C2.241 U C ~(2) 2.205 (2) 126.96 (7) 118.55 (7) 2.257 (2)
113.61 (7)
(PPh3)2CUCl.O.SC,H6" 2.260 (2) 2.208 (2) 125.48 (7) 120.74 (6) 2.272 2.240 2.255 (PPh3)2CUBr.0.SC6H6b 2.263 2.282 (PPh2-o-t01)2CuI 2.255 (PPhJ2CuI" 2.273
(PPh2-o-tol),CuBr
12) (2j (2) (2) (3) (1) (2)
113.76 (7) 2.336 (1) 127.89 (7) 118.25 (6) 112.52 (6) 2.346 (2) 126.0 (1) 121.0 (1) 112.8 (1) 2.507 (1) 126.36 (7) 116.82 (4) 2.524 (2) 126.9 (1) 116.61 (5)
'Reference 16. bReference 17.
Hb b
33
Figure 3. View of the molecule of PPh2-o-tol. 20% thermal ellipsoids are shown in this and subsequent figures. Hydrogen atoms have an arbitrary radius of 0.1 A.
87, 78, and 85'; P(0-tol), molecule 1, 84, 78, 86'; P(o-tol), molecule 2,79,89, and 86'. The consequent twisting of the phenyl rings about the P-C bonds, defined here by the angles between the normals to the base of the PC3pyramid and the planes of each phenyl group, are similar in PPh, and PPh2-o-to1 and range between 20 and 60°, with the twist about P-C always being in the same sense: PPh,, 22, 54, and 25'; PPh2-o-tol, 36, 26, and 47'. The almost C, symmetry adopted by both P(o-tol)3 molecules reflects the steric influence of the three tolyl groups on the conformational structure (molecule 1, 37,49, and 43'; molecule 2, 5 5 , 47, and 51'). In these molecules each ring is bent toward the lone pair with the angle P-C(1)-C(2) being 7-10' smaller than P-C(1)-C(6). For example with PPh3, the P-C(1)-C(2) angles are 115.8 (4), 116.3 (4), and 116.2 (4)' and the P-C(1)-C(6) angles are 124.9 (4), 123.9 (4), and 123.2 ( 4 ) O while
d Figure 4. (a) Projection of (PPh2-o-tol),CuCIonto the P2CuCIplane. (b) Projection of (PPh2-o-tol)2CuIonto the P2CuI plane.
in the present structure these angles are 117 (l), 115 ( l ) , and 116 (1)' and 123 ( l ) , 125 ( l ) , and 125 (1)O, respectively. In the (PPh2-o-tol),CuX complexes, the P-C distances are marginally shorter and the C-P-C angles slightly greater than the values found for the uncomplexed ligand: C1, (P-C) = 1.820 (2) A, (C-P-C) = 103.9 (2)O; Br, (P-C) = 1.816 (3) A, (CP-C) = 103.8 (4)'; I, (P-C) = 1.829 (2) A, (C-P-C) = 103.9 (6)'. Complexation results in a significant diminution of the differences between P-C(1)-C(2) and P-C( 1)-C(6) with the average difference in these angles for each of the three structures being 3.0, 3.3, and 3.7' respectively. In the triphenylphosphine complexes (PPh,),CuX, the phenyl groups of each ligand assumes the "W" conformation (I) in which
o,,/LPx> /\
/\
1
ring 1 of each ligand approaches coplanarity with the P2CuX
3538 Inorganic Chemistry, Vol. 26, No. 21, 1987 plane, the conformational angle, X-Cu-P(I)-C(Il l ) , ranging between 0 and 13O and the torsion angle of ring 1, Cu-P(I)-C(Il)-C(l12), varying between 17 and 39O. X-H(l12) contact distances are of the order of 2.7-2.9 A. The geometry of the PzCuX core in these compounds was found to be unsymmetrical for the chloride and bromide, with differences of 5-9O in the X-Cu-P angles and small but consistent differences of 0.01-0.02 A in the Cu-P distances, but symmetrical for the iodide, which crystallizes in a C2/c lattice with the Cu-I lying on a 2-fold axis of symmetry. In the present compounds, this conformational structure is not adopted. In both the chloride and bromide, each ligand adopts a skewed conformation with XCu-P(Z)-C(Il1) ranging from 26 to 33O, each ring being rotated to opposite sides of the P2CuX plane (Table VII). For ligand 1, there are quite short X-H( 112) contact distances (Cl, 2.7 A; Br, 2.8 A) for ring 1 and the Cu-P( 1)-C( 111)-( 112) torsion angles are 20 and 23O, respectively, well within the range recorded for the analogous PPh, compounds, while the tolyl group is located in ring 3. For ligand 2, however, the tolyl group is found in ring 1, which in turn is twisted away from the halogen with torsion angles of 53 (Cl) and 5 4 O (Br). In this conformation there are no methyl hydrogen-halogen contact distances less than 3.0 A. In the iodide structure the tolyl group is located in ring 1 of the two symmetry-related ligands. As in ligand 2 of the chloride and bromide structures, this ring has a torsion angle greater than 50' with no short X.-H contact distances. The angle I-Cu-P(1)-C(1 11) of 14' is, however, midway between the eclipsed and skewed conformations of (PPh3)$uX and (PPh2-o-tol)2CuCl,Br, respectively. Consideration of the PzCuX core geometries shows that the Cu-P distances in both the chloride and bromide are unsymmetrical (Cl, 2.241 (2) and 2.257 (2) A; Br, 2.240 (2) and 2.255 (2) A) and are -0.02 A shorter than the distances in the comparable PPh, complexes, as are the values for the iodide structure (2.255 (1) vs 2.273 (2) A) (Table VIII). The variation in Cu-P distance with halide is even smaller than that found for the PPh, compounds. The P-Cu-P angles of 126.96 (7) and 127.89 (7)' for X = C1 and Br are ca. 2' greater than in the PPh3 molecules, but this slight difference disappears for the iodide structures. In spite of the decrease in the Cu-P bond lengths, the Cu-X distances are also slightly shorter, the differences being 0.017 A for the iodide structures, decreasing to 0.010 A for the bromides and 0.003 A for the chlorides, a possible influencing factor being changes in the influence of X--H interactions on the Cu-X bond length. The shorter Cu-I distance is consistent with the increased wavenumber observed for the Cu-I vibrational mode. The
Bowmaker et al. asymmetry in H--X interactions is reflected in the C1,Br-Cu-P angles: C1, 118.55 (7) and 113.61 (7)O; Br, 118.25 (6) and 112.52 (6)O. Conclusions. Despite the significant conformational changes detailed above, the net effect on the core geometry of substituting a phenyl group of PPh, by an o-tolyl group is surprisingly small. Nevertheless, changes in the steric profile and X-H interactions caused by the introduction of this group into the ligand appears to result in a considerable simplification of the chemistry of adducts with CuX with three being the maximum coordination number of the copper atom attained. Preliminary X-ray results on reaction mixtures with 1:l molar ratios of ligand to CuX show the crystalline products obtained to be the 1:l dimeric species (PPhz-otol)CuXzCu(PPh2-o-to1).26 As yet, we have no evidence for the formation of the 1.5:l species commonly found for the PPh, system. Similarly, we have not been able to isolate 3:l monomers by recrystallization from excess ligand. Examination of molecular models shows that situations in which the copper atom is fourcoordinate, either in 3:l monomers, 1S:l dimers, or 1:l tetramers, results in considerable overlap of the methyl hydrogens with the other ligands. However, positive evidence for the existence or otherwise of four-coordinated copper species in this system must await a detailed solution equilibrium study similar to that recently reported for the PPh3 and PPhzMe system^.^'
Acknowledgment. We acknowledge support of this work by a grant from the Australian Research Grants Scheme. The Bruker CXP-300 spectrometer is operated by the Brisbane NMR Centre, and we thank the Centre for making instrumental time available to us and Dr. Andrew Whittaker for recording the solid-state spectra. We thank Catherine Hobbis for capable assistance in the recording of the far-infrared spectra. Microanalyses were completed by the University of Queensland Microanalytical Service. Registry No. (PPh2-o-tol)2CuC1, 110142-27-3; (PPh,-~-tol)~CuBr, 110142-28-4; (PPh2-0-t01)2CuI, 110142-29-5; PhZP-0-tol, 5931-53-3; Ph2PC1, 1079-66-9; CH,C6H,MgCl, 33872-80-9. Supplementary Material Available: Tables Sup I-Sup XII, listing non-hydrogen thermal parameters, the derived hydrogen positions, and ligand non-hydrogen geometries (1 8 pages); tables of calculated and observed structure factors (39 pages). Ordering information is given on any current masthead page.
(26) Engelhardt, L. M.; Healy, P C.; Kildea, J. D.; White, A. H., unpublished data. (27) Fife, D. J.; Moore, K. W. Inorg. Chem. 1984, 23, 1684.
